cifs: Autogenerate SMB2 error mapping table

Autogenerate the SMB2 status to error code mapping table, from the
smb2status.h common header, sorting it by NT status code so that it can be
searched by binary chopping. This also reduces the number of places this
list is duplicated in the source.

Signed-off-by: David Howells <dhowells@redhat.com>
cc: Steve French <stfrench@microsoft.com>
cc: ChenXiaoSong <chenxiaosong@kylinos.cn>
cc: linux-cifs@vger.kernel.org
Signed-off-by: ChenXiaoSong <chenxiaosong@kylinos.cn>
Reviewed-by: David Howells <dhowells@redhat.com>
Link: https://lore.kernel.org/linux-cifs/20260106071507.1420900-3-chenxiaosong.chenxiaosong@linux.dev/
Signed-off-by: Steve French <stfrench@microsoft.com>

Author: dhowells

fs/smb/client/Makefile

@@ -43,3 +43,17 @@ cifs-$(CONFIG_CIFS_ALLOW_INSECURE_LEGACY) += \
 	smb1transport.o
 
 cifs-$(CONFIG_CIFS_COMPRESSION) += compress.o compress/lz77.o
+
+#
+# Build the SMB2 error mapping table from smb2status.h
+#
+$(obj)/smb2_mapping_table.c: $(src)/../common/smb2status.h \
+			    $(src)/gen_smb2_mapping
+	$(call cmd,gen_smb2_mapping)
+
+$(obj)/smb2maperror.o: $(obj)/smb2_mapping_table.c
+
+quiet_cmd_gen_smb2_mapping = GEN     $@
+      cmd_gen_smb2_mapping = perl $(src)/gen_smb2_mapping $< $@
+
+clean-files	+= smb2_mapping_table.c

fs/smb/client/gen_smb2_mapping

@@ -0,0 +1,86 @@
+#!/usr/bin/perl -w
+# SPDX-License-Identifier: GPL-2.0-or-later
+#
+# Generate an SMB2 status -> error mapping table,
+# sorted by NT status code (cpu-endian, ascending).
+#
+# Copyright (C) 2025 Red Hat, Inc. All Rights Reserved.
+# Written by David Howells (dhowells@redhat.com)
+#
+use strict;
+
+if ($#ARGV != 1) {
+	print STDERR "Format: ", $0, " <in-h-file> <out-c-file>\n";
+	exit(2);
+}
+
+my %statuses = ();
+my @list = ();
+
+#
+# Read the file
+#
+open IN_FILE, "<$ARGV[0]" || die;
+while (<IN_FILE>) {
+	chomp;
+
+	if (m!^#define\s*([A-Za-z0-9_]+)\s+cpu_to_le32[(]([0-9a-fA-Fx]+)[)]\s+//\s+([-A-Z0-9_]+)!) {
+		my $status = $1;
+		my $code = $2;
+		my $ncode = hex($2);
+		my $error = $3;
+		my $s;
+
+		next if ($status =~ /^STATUS_SEVERITY/);
+
+		die "Duplicate status $status"
+			if exists($statuses{$status});
+
+		my %s = (
+			status => $status,
+			code   => $code,
+			ncode  => $ncode,
+			error  => $error
+		);
+		$statuses{$status} = \%s;
+		push @list, \%s;
+	}
+}
+close IN_FILE || die;
+
+
+@list = sort( { $a->{ncode} <=> $b->{ncode} } @list);
+
+open OUT_FILE, ">$ARGV[1]" || die;
+my $list_size = scalar @list;
+my $full_status = "";
+for (my $i = 0; $i < $list_size; $i++) {
+	my $entry = $list[$i];
+	my $status = $entry->{status};
+	my $code   = $entry->{code};
+	my $ncode  = $entry->{ncode};
+	my $error  = $entry->{error};
+
+	next if ($ncode == 0);
+
+	$full_status .= $status;
+	# There may be synonyms
+	if ($i < $list_size - 1) {
+		my $next_entry = $list[$i + 1];
+		my $next_ncode = $next_entry->{ncode};
+		if ($next_ncode == $ncode) {
+			$full_status .= " or ";
+			next;
+		}
+	}
+
+	my $pad = " ";
+	if (length($full_status) < 40) {
+		my $n = 40 - length($full_status);
+		$pad = "\t" x ((($n-1) / 8) + 1);
+	}
+	print(OUT_FILE "{ $code, $error, \"$full_status\" },\n");
+
+	$full_status = "";
+}
+close OUT_FILE || die;